Aphids feeding on true fir
Feeding by aphids can cause needles and new shoots to twist and distort in shape.
Aphids feed on conifers by sucking juices from branches, shoots and needles. Feeding from aphids can cause the foliage to become curled. Heavily affected trees may lose their needles.
Leader of concolor fir showing curled, twisted needles caused by aphids feeding.
Some of the common, conifer-feeding aphids produce lots of honeydew that leads to black sooty mold. On the other hand, there are many insect predators who relish aphids. Often, aphid problems take care of themselves – the predators knock the population way down fairly rapidly. The exception is when ants are present – they will protect the aphids from the predators.
Woolly, white to light green aphids at base of needles.
On many true firs such as concolor, corkbark and grand fir, we are currently finding a woolly aphid that is thought to be Balsam twig aphid. When we find this aphid, we don’t usually see much damage even with high populations. Michigan State University Extension suggests that growers should monitor their trees if they have high populations and the trees will be harvested this year; they may want to apply an insecticide.